In the Garden:Southwestern Deserts
June, 2005
Regional Report

These compost bins were constructed from shipping palettes by a Maricopa County Master Gardener. Doors with handles slide up and out for easy access.

Composting: Sustainable Gardening Extraordinaire

If you've been around a gathering of gardeners, it's likely that conversation turned to the glories of "gardener's gold," known less flamboyantly as compost. The best thing you can do to create a healthy, sustainable soil over time is to add compost to garden beds before each planting season.

Here in the southwest we recommend layering 4 to 6 inches on top of the bed and then turning it under to a depth of at least 12 inches. That may seem like a lot of compost, but our native soils typically contain less than one-half of one percent organic matter, so it's essential to add it to garden beds to grow annual vegetables and flowers.

Compost increases the water- and fertilizer-holding capacity of sandy soils and improves drainage in clay soils. It adds nutrients and increases the activity of soil microbes. Gardeners new to the desert sometimes lament the lack of earthworms that they were used to seeing when they dug into the soil in other regions. Well, if you add compost to your beds, they will come. Compost makes the soil more workable and adds a pleasant, earthy smell.

Making compost is a way of taking sustainable gardening practices a step further than simply improving the soil. Composting provides a valuable use for tons of organic matter that would otherwise end up in the landfill. In the southwest, about 40 percent of refuse in the landfill is organic matter that could be composted: grass clippings, woody trimmings from trees and shrubs, dried leaves, green trimmings of spent annuals, coffee grounds, fruit and vegetable scraps from the kitchen, shredded paper, and more.

Make Your Own Bin
Another sustainable aspect of composting is reusing items to form the compost bins, saving yet another load to the landfill. Of course, compost doesn't require a container in which to decompose, but fixed boundaries can keep the pile in a tidier heap. Bins also can be attractive and a fun outlet for creativity. In schoolyards I've seen many gloriously colorful bins handpainted by the kids.

Many cities reuse old garbage cans by cutting off the bottoms and/or punching holes in the sides. These are given to residents for free or a few dollars to use as bins. (Check with your city waste department to see what's offered.) If someone in your neighborhood is knocking down a brick or block wall, don't let the materials go to waste. They make excellent 3-sided bins. Reuse chicken wire or hardware cloth as circular bins.

There must be thousands of wooden shipping palettes discarded every day. Ask at a local store if you can carry a few away. A compost pile should be at least 3 feet by 3 feet by 3 feet (1 cubic yard) to have enough mass to insulate and retain heat, and shipping palettes are the perfect size. Four palettes make one bin; 10 palettes make the classic 3-bin configuration that allows you to have a place for fresh material, one in the process of decomposing, and a finished product, all side by side.

Finally, composting is good exercise, helping to sustain not only the garden over the long haul, but the gardener as well!